5 research outputs found
Three New Three-Dimensional Frameworks Based on Hepta‑, Hexa‑, and Pentanuclear Cobalt Clusters Derived from Substituted Isophthalic Acids: Synthesis, Structures, and Magnetic Properties
Three new cluster-based cobalt/carboxylate
frameworks, formulated as {[H<sub>3</sub>O]Â[Co<sup>II</sup><sub>7</sub>Â(μ<sub>3</sub>-OH)<sub>3</sub>Â(MeO-ip)<sub>6</sub>Â(H<sub>2</sub>O)<sub>3</sub>]·4.5H<sub>2</sub>O}<sub><i>n</i></sub> (<b>1</b>), {[Co<sup>II</sup><sub>6</sub>Â(μ<sub>3</sub>-OH)<sub>2</sub>Â(Bu<sup>t</sup>-ip)<sub>4</sub>Â(Bu<sup>t</sup>-Hip)<sub>2</sub>Â(H<sub>2</sub>O)<sub>2</sub>]·2CH<sub>3</sub>CN}<sub><i>n</i></sub> (<b>2</b>), and {[Co<sup>II</sup><sub>5</sub>(Me-ip)<sub>4</sub>Â(Me-Hip)<sub>2</sub>Â(H<sub>2</sub>O)<sub>4</sub>]·6H<sub>2</sub>O}<sub><i>n</i></sub> (<b>3</b>) (MeO-H<sub>2</sub>ip = 5-methoxyisophthalic
acid, Bu<sup>t</sup>-H<sub>2</sub>ip = 5-<i>tert</i>-buthylisophthalic
acid, and Me-H<sub>2</sub>ip = 5-methylisophthalic acid) have been
synthesized by the hydroÂ(solvo)Âthermal reactions of Co<sub>2</sub>(CO)<sub>8</sub> with the corresponding isophthalic acids in CH<sub>3</sub>CN, Pr<sup><i>i</i></sup>OH, and water. Single-crystal
X-ray diffraction studies reveal that <b>1</b> and <b>2</b> both exhibit a three-dimensional (3D) <b>pcu</b> net based
on hepta- and hexanuclear cobalt hydroxyl clusters {Co<sup>II</sup><sub>7</sub>(μ<sub>3</sub>-OH)<sub>3</sub>} and {Co<sup>II</sup><sub>6</sub>(μ<sub>3</sub>-OH)<sub>2</sub>}, respectively.
Compound <b>3</b> is a 3D porous framework with an eight-connected <b>bcu</b> topology constructed from a pentanuclear cobalt cluster.
It has been found that the structures of cobalt clusters in these
compounds largely depend on the substituents on isophthalic acids.
The magnetic studies indicate that both <b>1</b> and <b>2</b> show spin-canting antiferromagnetism, while <b>3</b> exhibits
a magnetocaloric effect (MCE). The resulting entropy change of <b>3</b> is 13.23 J kg<sup>–1</sup> K<sup>–1</sup> for
Δ<i>H</i> = 80 kG at 4 K
Synthesis and Structure of Two Acentric Heterometallic Inorganic–Organic Hybrid Frameworks with Both Nonlinear Optical and Ferroelectric Properties
Solvothermal reactions of CdÂ(NO<sub>3</sub>)<sub>2</sub>·4H<sub>2</sub>O with aromatic polycarboxylic
acids in the presence of sodium
nitrate led to two acentric three-dimensional (3D) heterometallic
inorganic–organic hybrid frameworks, namely, [Me<sub>2</sub>NH<sub>2</sub>]Â[Cd<sub>2</sub>Na<sub>3</sub>(2,4-PYDC)<sub>4</sub>]·2H<sub>2</sub>O (<b>1</b>) and [Me<sub>2</sub>NH<sub>2</sub>] [CdNaÂ(OH-<i>m</i>-BDC)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]·2H<sub>2</sub>O (<b>2</b>) (2,4-H<sub>2</sub>PYDC = 2,4-pyridinedicarboxylic acid, OH-<i>m</i>-H<sub>2</sub>BDC = 5-hydroxyisophthalic acid). The framework of <b>1</b> is constructed by a 3D inorganic Cd–Na connectivity,
which resembles a concrete reinforcement structure and features a
{CdNa}<sub><i>n</i></sub> rod-shaped chain, a {CdNa<sub>2</sub>}<sub><i>n</i></sub> helical chain, and a 20-membered
{Cd<sub>6</sub>Na<sub>14</sub>} ring. Compound <b>2</b> is built
up by one-dimensional inorganic {CdNa}<sub><i>n</i></sub> rod-shaped chains which are further connected by OH-<i>m</i>-BDC<sup>2–</sup> ligands, affording a 3D polymeric framework.
Compounds <b>1</b> and <b>2</b> crystallize in acentric
space groups, and both display powder second harmonic generation efficiencies
approximately 0.8 and 0.7 times, respectively, than that of the potassium
dihydrogen phosphate (KDP) powder. In addition, they also exhibit
luminescence and potential ferroelectric properties
Synthesis and Structure of Two Acentric Heterometallic Inorganic–Organic Hybrid Frameworks with Both Nonlinear Optical and Ferroelectric Properties
Solvothermal reactions of CdÂ(NO<sub>3</sub>)<sub>2</sub>·4H<sub>2</sub>O with aromatic polycarboxylic
acids in the presence of sodium
nitrate led to two acentric three-dimensional (3D) heterometallic
inorganic–organic hybrid frameworks, namely, [Me<sub>2</sub>NH<sub>2</sub>]Â[Cd<sub>2</sub>Na<sub>3</sub>(2,4-PYDC)<sub>4</sub>]·2H<sub>2</sub>O (<b>1</b>) and [Me<sub>2</sub>NH<sub>2</sub>] [CdNaÂ(OH-<i>m</i>-BDC)<sub>2</sub>(H<sub>2</sub>O)<sub>2</sub>]·2H<sub>2</sub>O (<b>2</b>) (2,4-H<sub>2</sub>PYDC = 2,4-pyridinedicarboxylic acid, OH-<i>m</i>-H<sub>2</sub>BDC = 5-hydroxyisophthalic acid). The framework of <b>1</b> is constructed by a 3D inorganic Cd–Na connectivity,
which resembles a concrete reinforcement structure and features a
{CdNa}<sub><i>n</i></sub> rod-shaped chain, a {CdNa<sub>2</sub>}<sub><i>n</i></sub> helical chain, and a 20-membered
{Cd<sub>6</sub>Na<sub>14</sub>} ring. Compound <b>2</b> is built
up by one-dimensional inorganic {CdNa}<sub><i>n</i></sub> rod-shaped chains which are further connected by OH-<i>m</i>-BDC<sup>2–</sup> ligands, affording a 3D polymeric framework.
Compounds <b>1</b> and <b>2</b> crystallize in acentric
space groups, and both display powder second harmonic generation efficiencies
approximately 0.8 and 0.7 times, respectively, than that of the potassium
dihydrogen phosphate (KDP) powder. In addition, they also exhibit
luminescence and potential ferroelectric properties
Unusual High Thermal Stability within a Series of Novel Lanthanide TATB Frameworks: Synthesis, Structure, and Properties (TATB = 4,4′,4″-s-Triazine-2,4,6-triyl-tribenzoate)
A series of multifunctional lanthanide-organic frameworks
LnÂ(TATB)Â(H<sub>2</sub>O) (Ln = Y <b>1</b>, Eu <b>2</b>, Gd <b>3</b>, Tb <b>4</b>, Dy <b>5</b>, Ho <b>6</b>, and Er <b>7</b>; TATB = 4,4′,4″-s-triazine-2,4,6-triyl-tribenzoate) with an unprecedented (4,8)-connected topology have been synthesized
and characterized. The structures of these compounds were determined
by single crystal X-ray diffraction and their thermal stability, sorption,
as well as luminescent and magnetic properties were also investigated.
Compounds <b>1</b>–<b>7</b> are isomorphic and
present an open non-interpenetrated three-dimensional microporous
framework constructed by infinite dinuclear-based, rod-shaped lanthanide-carboxylate
secondary building units (SBUs) which arranged in nearly mutually
perpendicular directions and interwoven by TATB linkers. All these
compounds exhibit very high thermal stability and are stable up to
550 °C. The pore characteristics and gas sorption properties
of these compounds were studied by experimentally measuring different
gases (CO<sub>2</sub>, N<sub>2</sub>, and H<sub>2</sub>) and different
solvent molecules (H<sub>2</sub>O and CH<sub>3</sub>OH). The luminescent
properties of compounds <b>1</b>–<b>7</b> in the
solid state were investigated. The results show that <b>2</b> and <b>4</b> exhibited relatively high quantum yields and
lifetime values, suggesting that they could be good candidates for
light-emitting diodes (LEDs) and light applications. The variable-temperature
magnetic studies show that the magnetic interaction between the LnÂ(III)
ions in <b>2</b>–<b>7</b> was mainly due to the
antiferromagnetic coupling as well as the depopulation of the Stark
levels. The spin–orbit coupling parameter λ for EuÂ(III)
(472 cm<sup>–1</sup>) has been obtained for <b>2</b>.
The in-phase and out-phase signals <i>χ′</i><sub>M</sub><i>T</i> and <i>χ″</i><sub>M</sub> of <b>5</b> exhibit frequency dependence
Unusual High Thermal Stability within a Series of Novel Lanthanide TATB Frameworks: Synthesis, Structure, and Properties (TATB = 4,4′,4″-s-Triazine-2,4,6-triyl-tribenzoate)
A series of multifunctional lanthanide-organic frameworks
LnÂ(TATB)Â(H<sub>2</sub>O) (Ln = Y <b>1</b>, Eu <b>2</b>, Gd <b>3</b>, Tb <b>4</b>, Dy <b>5</b>, Ho <b>6</b>, and Er <b>7</b>; TATB = 4,4′,4″-s-triazine-2,4,6-triyl-tribenzoate) with an unprecedented (4,8)-connected topology have been synthesized
and characterized. The structures of these compounds were determined
by single crystal X-ray diffraction and their thermal stability, sorption,
as well as luminescent and magnetic properties were also investigated.
Compounds <b>1</b>–<b>7</b> are isomorphic and
present an open non-interpenetrated three-dimensional microporous
framework constructed by infinite dinuclear-based, rod-shaped lanthanide-carboxylate
secondary building units (SBUs) which arranged in nearly mutually
perpendicular directions and interwoven by TATB linkers. All these
compounds exhibit very high thermal stability and are stable up to
550 °C. The pore characteristics and gas sorption properties
of these compounds were studied by experimentally measuring different
gases (CO<sub>2</sub>, N<sub>2</sub>, and H<sub>2</sub>) and different
solvent molecules (H<sub>2</sub>O and CH<sub>3</sub>OH). The luminescent
properties of compounds <b>1</b>–<b>7</b> in the
solid state were investigated. The results show that <b>2</b> and <b>4</b> exhibited relatively high quantum yields and
lifetime values, suggesting that they could be good candidates for
light-emitting diodes (LEDs) and light applications. The variable-temperature
magnetic studies show that the magnetic interaction between the LnÂ(III)
ions in <b>2</b>–<b>7</b> was mainly due to the
antiferromagnetic coupling as well as the depopulation of the Stark
levels. The spin–orbit coupling parameter λ for EuÂ(III)
(472 cm<sup>–1</sup>) has been obtained for <b>2</b>.
The in-phase and out-phase signals <i>χ′</i><sub>M</sub><i>T</i> and <i>χ″</i><sub>M</sub> of <b>5</b> exhibit frequency dependence